Customizing the Look & Buttons in Shopping Cart & Product Pages

Hi there,

MarketPress doesn't naturally look good with my theme, so I'd like some help to replace the buttons, change colors, etc. I made .gif buttons to replace the current ones with, but I don't know how to add them. I think in the next build you should allow people to easily upload their own buttons, and change link colors.

I also want to make the description here be next to the image:

I want to make two clear boxes here, one for login and one for continue without an account... right now they are too squished together and unclear:

Thank you!